Secondary Battery Laminate Film with Protective Material
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Solution Overview
Problem
Conventional secondary batteries using metal cans as exterior bodies are heavy and difficult to manufacture into thin forms, and when using laminate films, the current collector and active material layers are susceptible to damage from external forces, leading to potential breakage.
Innovation Solution
A secondary battery design incorporating a laminate film exterior body with a protective material strategically placed around the current collector projections to absorb and distribute external forces, preventing damage and maintaining structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metal can is used as an exterior body, then the secondary battery has high strength, but the weight increases and it becomes difficult to manufacture a thin form
Solution Approach 1:
The patent replaces the rigid metal can with a flexible laminate film consisting of multiple layers including metal foil and resin. This thin film structure provides sufficient mechanical strength while dramatically reducing weight and enabling thin battery design, directly resolving the contradiction between strength and weight.
Solution Approach 2:
The exterior body uses a composite laminate film structure combining metal foil (for strength) with resin layers (for flexibility and sealing). This composite approach achieves the required mechanical strength without the weight penalty of solid metal cans, solving both weight and thinness requirements.
2Length of moving object
If a thin laminate film is used as an exterior body, then the secondary battery becomes thinner and lighter, but the current collector and active material layers are susceptible to damage from external forces
Solution Approach 1:
The patent places a protective material between the current collector projection and the exterior body to cushion against external forces before they can damage the current collector. This preventive cushioning protects the thin battery structure while maintaining its thin profile.
Solution Approach 2:
The protective material acts as an intermediary element between the external environment and the vulnerable current collector projection. It mediates the mechanical stress, distributing and reducing the force applied to the current collector, thereby preventing cracks and breakage.
3Ease of manufacture
If the current collector projection is exposed without protection, then the manufacturing process is simpler, but the projection is susceptible to cracking when the battery is bent
Solution Approach 1:
The protective material is positioned in advance to cover the current collector projection before the battery undergoes bending or external stress. This pre-positioned protection prevents cracks during manufacturing and usage without significantly complicating the manufacturing process.
Solution Approach 2:
The protective material is applied locally only where needed - at the current collector projection area susceptible to bending damage - rather than uniformly across the entire battery. This localized approach provides necessary protection while minimizing additional manufacturing complexity.
Data Source
AI summary
In the case where a film, which has lower strength than a metal can, is used as an exterior body of a secondary battery, a current collector provided in a region surrounded by the exterior body, an active material layer provided on a surface of the current collector, or the like might be damaged when force is externally applied to the secondary battery. A secondary battery that is durable even when force is externally applied thereto is provided. A region that is easily partly bent and a region that is not easily partly bent owing to a protective material provided in the region are intentionally formed to obtain the durable secondary battery.